One thing to bear in mind is that most Portuguese (and as such I presume Spanish) keyboards have superscript letters readily available. In English, there are only awkward shortcuts.
– BladorthinTheGreyOct 14 '16 at 21:24

@BladorthinTheGrey I'm not even sure if this is the symbol ª or the superscript a. (Although, you also see them underlined in Spain, which suggests it is a symbol.) According to Wikipedia (elsewhere) they are not to be confused.
– ŘídícíOct 14 '16 at 21:26

3

In a statement such as yours, explaining the usage, it's acceptable; whether it should be classified as 'English' is debatable (but surely ignorable, if you say so). I certainly wouldn't use it without explanation.
– Edwin AshworthOct 14 '16 at 21:28

3

I wouldn't use it. Native English speakers won't know what it means even though abbreviations such as J<sup>as</sup> (James) were common in the past.
– MickOct 14 '16 at 21:44

2 Answers
2

So-called "superscript contractions" used to be a common practice in English, when handwriting was much more common, but it is now considered obsolete.
This Cambridge course on early Modern English handwriting gives the following advice to students:

superscript characters, often a form of contraction which may imply preceding omitted characters, as in wch for 'which'. Other common contractions of this type include yr for 'your' or 'yowr'; Sr for 'Sir' and Mr for 'Master'; wt or wth for 'with' (and wthout for 'without'); maty for 'maiesty' or maties for 'maiesties'; and words ending in -mt for '-ment', such as gouernemt for 'gouernement' or parliamt for 'parliament'.

Wikipedia glosses over this practice, giving nothing useful to quote.

This practice also extended to personal names, for example J os for Joseph or Wm for William. The following excerpt from an 1877 land atlas contains at least 3 examples that I can see:

It was mostly an artifact of handwriting, occasionally printed, but fell out of use with automated typesetting. Nowadays you see them in only a few places such as ordinals (1st , 2nd , 3rd ) and special symbols such as the TrademarkTM symbol.

So to actually answer your question, a few people might recognize what you're trying to do, but they would find it odd or contrived. The rest would just be confused.

In English, there are slang names for full names, such as Bob/Robert, Bill/William, Dick/Richard, Jim/James, Joe/Joseph, Tim/Timothy, Chris/Christopher, Ron/Ronald, Ted or Teddy/Edward, Tony/Anthony, Dave/David, etc.

Other than that, we use the full name, and would defer to other languages' naming conventions.

People though, unless they know Spanish naming conventions, wouldn't know what that means, so you'll have to clarify that beforehand to your audience.

This isn't about familiar diminutives of names, but a purely orthographic abbreviation. The difference is that Bob, Ted, and similar names are pronounced varieties committed to writing; José Mª is read out loud as José María just like mr. is read out loud as mister.
– Janus Bahs JacquetOct 15 '16 at 20:24

And this wouldn't translate to English speakers.
– DES-COAOct 15 '16 at 20:37